Foot or top plate assembly

ABSTRACT

A foot or top plate assembly for a shoring structure or tower comprises a wedged pin, a screw jack having an end adapted to receive the wedged pin in a friction fit, a foot plate having a first support for receiving the wedged pin in a friction fit and a second support for supporting the wedged pin. The first and second supports adapted to receive the hollow end in a sliding fit. The wedged pin connects the foot plate to the screw jack, whereby as the wedged pin is moved between an engaged position and a disengaged position the base plate moves relative to the screw jack.

FIELD OF INVENTION

This invention relates to a foot or top plate assembly for a shoringstructure or tower. In particular, this invention relates to an assemblycapable of supporting heavy loads and capable of quickly releasing toreduce the pressure forces acting on screw jacks supporting the shoringstructure or tower.

DESCRIPTION OF THE PRIOR ART

Scaffolding can be assembled to construct platforms for workers,equipment and materials and also for shoring or support structures.Scaffolding usually consists of frames, saddlebeams and crossbracingwhich can be interconnected to form a shoring structure or tower. Theframes are mounted on screw jacks to accommodate the shoring structureor tower to the support surface. The operation and details ofscaffolding and connectors are more particularly described in U.S. Pat.Nos. 4,470,574 and 5,112,155.

Screw jacks are used to raise or lower the shoring structure or tower.Screw jacks generally comprise a shaft having a thread on the externalsurface and a wing nut. The screw jack shaft fits inside of a hollowframe while the frame rests on the wing nut. The shoring structure ortower is then raised or lowered by screwing and unscrewing the wing nutalong the threaded shaft.

In many construction applications, the load on each leg of the shoringstructure or tower does not normally exceed 4,500 kg (10,000 pounds).However during the construction of large concrete structures such asdams or bridges, a shoring structure or tower is required to support theforms and the poured concrete. The loading on the shoring structure ortower can easily exceed 6,000 kg (13,500 pounds) per leg.

The wing nuts of the screw jacks can be easily manipulated for loadingup to approximately 2,600 kg (6,000 pounds) per jack. However when theshoring structure or tower is subjected to heavier loads, the wing nutsof the screw jacks become difficult to unscrew. The loading pressure onthe screw prevents the wing nut from being retracted along the screwthread. Consequently, it becomes very difficult to retract the nutwithout damaging the nut.

A coarser threading on the screw jack could be selected which willpermit the unscrewing of the wing nut under reasonably heavier loads.However, the greater the pitch of the thread, the more difficult andtime consuming it is to raise the shoring structure or tower foradjustment. Under extreme loading and with a coarse thread, the wing nutmay still be difficult to unscrew.

Hollow pipes or tubes can be applied to one of the wings of the wing nutto increase the turning leverage on the nut. Hammers are also used tounscrew the nut. However when the loading becomes extreme, the increasedleverage will often bend or shear off the wing and heavy hammer blowswill damage the nut. The end result is a sheared or damaged wing.

Footings for shoring structures or towers can be mounted in sandboxesfilled with sand. The sandboxes have plugged holes. The shoringstructure or tower is assembled and loaded with each foot mounted ineach sandbox. To relieve the pressure on the jacks, the holes in thesandboxes are unplugged allowing the sand to run out increasing theclearance between the support surface and the supported structurethereby reducing the load on the shoring structure or tower and jacks.The screw jacks may then be manipulated.

While the sandbox system does provide a system for unloading the screwjacks of the shoring structure or tower, the sandbox system is difficultand time consuming to set up and use. As a result, the moving, settingand storing of these sandboxes create additional expenses and requireadditional skill and effort to install.

SUMMARY OF THE INVENTION

The disadvantages of the prior art may be overcome by providing a footor top plate and screw jack assembly for a shoring frame which iscapable of being quickly reduced in relative length to reduce theloading thereon.

It is desirable to provide a foot and screw jack assembly which isconnected through a wedged pin having a wedged position inserted betweenthe screw jack and foot and adapted for transferring loads thereacrossand a disengaged position for transferring loads from the screw jackdirectly to the foot.

It further desirable to provide a wedged pin which is conical in shapewhereby the foot may pivot with respect to the screw jack.

According to one aspect of the invention, there is provided a foot ortop plate assembly comprising, a wedged pin, a screw jack having ahollow end adapted to receive the wedged pin in a friction fit, a footplate having a support means for receiving the wedged pin in a frictionfit and a pin support means for supporting the wedged pin and the firstand second support means adapted to receive the hollow end in a slidingfit, the wedged pin connecting the foot plate to the screw jack, wherebyas said wedged pin is moved between a fully engaged position and adisengaged position said base plate moves relative to the screw jack.

According to another aspect of the invention, there is provided a footor top plate assembly comprising,

a screw jack shaft having a hollow end and a threaded end, the threadedend having an external thread adapted to receive a wing nut, the hollowend having a first bore of a first diameter and a second bore of asecond diameter, the first bore in substantial alignment with the secondbore,

a base plate having a first and second support plate, the first supportplate having a third bore of a third diameter and the second supportplate having a fourth bore of a fourth diameter, the third bore insubstantial alignment with the fourth bore, the first plate spaced fromthe second plate for slidingly receiving the hollow end of the screwjack, and

a wedged pin for extending through the bores, the bores adapted toreceive the wedged pin in a frictional fit, the base plate having a pinsupport member extending substantially perpendicular thereto and adaptedfor supporting the wedged pin intermediate of the first and secondsupport plate, the wedged pin connecting the base plate to the screwjack, whereby as the wedged pin is moved between a fully engagedposition and a disengaged position the base plate moves relative to thescrew jack.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, as exemplified by a preferred embodiment, is describedwith reference to the drawings in which:

FIG. 1 is a perspective view of a shoring structure or tower includingthe foot assembly of the present invention;

FIG. 2 is a perspective view of the screw jack shaft of the invention ofFIG. 1;

FIG. 3 is an exploded perspective view of the foot and pin of theinvention of FIG. 1;

FIG. 4 is a cross-sectional view of the foot plate of the inventiontaken along plane 1--1 of FIG. 1;

FIG. 5 is a front elevational view of the footing of the invention ofFIG. 1 illustrating the foot in an engaged position;

FIG. 6 is a front elevation view of the footing of the invention of FIG.1 illustrating the foot in a disengaged position;

FIG. 7 is a front elevational view of the invention of FIG. 1illustrating the assembly in an engaged condition; and

FIG. 8: is a front elevational view of the invention of FIG. 1illustrating the assembly in a disengaged position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a shoring structure or tower is illustrated. Theshoring structure or tower comprises end frames 12 having hollow legs 14and cross beams 16. Frames 12 are joined together using cross-bracing 18and connectors 20. At the upper end of frames 12 are saddlebeams 22 andscrew jacks 24 for adapting the shoring structure or tower to supportvarious construction forms. At the lower end of legs 14 are footassemblies 26.

Referring to FIGS. 2, 7 and 8, foot assemblies 26 have a cylindricalshaft 28 which extends up into the hollow leg 14 of frame 12. Shaft 28has an external thread 30. Wing nut 32 is in threaded engagement withthread 30. Hollow legs 14 will rest on the wing nut 32. Shaft 28 has atone end a pair of bores 34 and 36 which are diametrically opposed. Bore34 has a diameter greater than that of bore 36, for reasons which willbecome apparent. Shaft 28 can be machined from an extruded tube ofaluminum.

Referring to FIG. 3, foot assemblies 26 has a rectangular base plate 38.Base 38 has two support plates 40 and 42 extending substantiallyperpendicular to base plate 38. Support plates 40 and 42 may bestructurally reinforced by providing flanges 44 and 46 at each endthereof. Base plate 38 can be casted using a carbon steel.

Base plate 38 may also have mounting platforms 45 having a bore 47 toreceive screws (not illustrated) to connect the foot assembly to a basesuch as an aluminum stringer or joist beam as illustrated in U.S. Pat.No. 4,470,574.

Support plate 40 has a bore 48 and support plate 42 has a concentricbore 50 defining a central axis substantially parallel to the base plate38. Bore 48 has a diameter greater than that of bore 50. The diametersof bores 34 and 36 will be substantially the same as are the diametersof bores 48 and 50, respectively. However in the preferred embodiment,the bores 48, 34, 36 and 50 diminish is size for reasons which areexplained below.

The bores 48 and 50 are spaced from the base plate 38 a distance whichexceeds the distance between bores 34 and 36 of shaft 28 and the hollowend of the shaft 28 to allow for relative movement therebetween. Supportplates 40 and 42 are spaced apart from each other. Shaft 28 is able tofit between support plates 40 and 42 in a sliding fit.

Pin support 51 extends between support plates 40 and 42 andsubstantially in line with the central axis. Pin support 51 has a lengthless than the inside diameter of shaft 28 allowing the pin support 51 toextend into the shaft 28.

Referring to FIGS. 3 and 4, a wedged pin 52 has a tapered shape whichhas a rate of taper corresponding to the difference in diameters anddistance between bores 48 and 50. The rate of taper will depend upon theexpected loads for the foot assembly, the amount of clearance which willbe required to unload the screw jacks and the diameter of the shaft ofthe screw jack. The rate of taper can be in the range of 2 and 10degrees. In the preferred embodiment, pin 52 has an elongated cone shapehaving a taper angle α of approximately 3 degrees. Pin 52 willfrictionally fit within bores 48 and 50 when in an engaged position.

Pin 52 has a bore 54 in the tapered end of the pin for receiving a pin56. Pin 56 is serpentine in shape to hold the pin 52 in place afterassembly. Pin 52 is preferably machined and polished from a carbonsteel.

Referring to FIGS. 5, foot assembly 26 has the connecting pin 52inserted through the bores 48 and 50 of base plate 38 and through bores34 and 36 of shaft 28. Bores 48 and 50 and 34 and 36 are tapered at thetaper angle α to frictionally receive the pin 52 when the pin 52 is inan engaged position. The upper surface of pin support 51 has a concavetop surface 58 for cradling and supporting the connecting pin 52.

The foot assembly 26 is assembled by aligning the bores 34 and 36 ofshaft 28 with the bores 48 and 50 of support members 40 and 42 and fullyinserting the pin 52 therethrough connecting the base plate 38 and shaft28 together. Pin 56 is inserted through bore 54 to lock the pin therein.Since the pin 52 is an elongated cone shape, base plate 38 is able topivot with respect to shaft 28. This feature is particularlyadvantageous in conditions where the support surface where the shoringstructure or tower is to be assembled is uneven.

In this engaged position, pin 52 will frictionally fit within bores 48,34, 36 and 50 and will be resting upon pin support 51. The screw jack isurged relatively away from the base plate 38. In this position, the footis capable of being loaded. The load is transmitted from the shaft 28 tothe pin 52 and then to the support plates 40 and 42 and the pin support51. In the preferred embodiment, each such foot may be loaded in excessof 11,300 kg (25,000 pounds).

Referring to FIGS. 6, 7 and 8, the footing assembly 26 is unloaded byforcing the connecting pin 52 towards the thicker end as indicated bythe arrow to a disengaged position. A hammer or other instrument may beused to forcibly move the pin 52 across. As the pin 52 moves across, theshaft 28 will move relatively towards the base plate 38 in a wedge-likemanner reducing the distance between the shaft 28 and base plate 38.Where the loading on the shoring structure or tower is stationary suchas in concrete pouring, the wedging of pin 52 will decrease the heightof the shoring structure or tower. Since concrete floor 60 remainsstationary, the compressive loads on the shoring structure or tower arereduced. After the pin 52 has been wedged outwardly to a disengagedposition, the wing nut 32 may be unscrewed to fully unload thescaffolding for disassembly. In a fully disengaged position, the shaft28 will rest directly on the base plate 38 for load transfer.

As illustrated in FIGS. 7 and 8, the foot assembly may also be installedat the head of the shoring structure or tower. By including the footassembly at the head, an increased amount of play or clearance may beachieved to further reduce the loading on the screw jack wing nuts.

It apparent that the pin 52 may have a rectangular or squarecross-section, provided the upper and lower surfaces were tapered in awedge shape. The bores 34, 36 and 48, 50 would require a correspondingcross-section to be efficient. However, the base plate would not be ableto pivot with respect to the screw jack.

It is also apparent that other material may be used for the componentsof the foot assembly. Hollow or solid steel may be used to manufacturethe shafts 28. Base plate 28 may be casted with iron or even aluminum ormay even be machined from such metals. Base plate 28 may also be of anydesired shape and size provided the base plate 28 adequately supportsand transfers the expected loads.

In the preferred embodiment, the taper angle α of approximately 3degrees is described. However depending on the loading requirements, ataper angle α of between 2 and 10 degrees may be used.

Although in the preferred embodiment the pin and corresponding boresthrough which the pin extends are described as being round, it isapparent that the pin and bores could be any configuration provided thepin is able to provide the wedge action required for the invention.

Although the disclosure describes and illustrates the preferredembodiments of the invention, it is understood that the invention is notlimited to these particular embodiments. Many variations andmodifications will now occur to those skilled in the art. For definitionof the invention, reference is made to the appended claims.

I claim:
 1. A foot or top plate assembly for a shoring structure or tower, said assembly comprising:a wedged pin having an elongated cone shape having a taper, a screw jack shaft having a hollow end adapted to receive the wedged pin in a friction fit in an engaged position, a base plate having a support means for receiving the wedged pin in a friction fit and said support means adapted to receive said hollow end in a sliding fit, said wedged pin pivotally connecting the base plate to the screw jack, whereby as said wedged pin is moved between said engaged position and a disengaged position relative movement between said base plate and said screw jack is effected.
 2. A foot or top plate assembly in claim 1 wherein said paper is between 2 to 10 degrees.
 3. A foot or top plate assembly as claimed in claim 2 wherein said support means is a first and second plate extending substantially perpendicular to the base plate and spaced apart to slidingly receive the screw jack.
 4. A foot or top plate assembly as claimed in claim 3 wherein said assembly further comprises a pin support means for supporting the wedged pin.
 5. A foot or top plate assembly as claimed in claim 4 wherein said pin support means is an abutment member extending substantially perpendicular to the base plate and spaced between said first and second plates and sized to extend into the hollow end, said pin support means adapted to support said wedged pin intermediate of the support means.
 6. A foot or top plate assembly as claimed in claim 5 wherein said hollow end has a first bore of a first diameter and a second bore of a second diameter, said first bore in transverse alignment with the second bore, said first plate has a third bore of a third diameter and said second plate has a fourth bore of a fourth diameter, said third bore in substantial alignment with the fourth bore, and the rate of difference in the said diameters corresponds to the taper of the wedged pin.
 7. A foot or top plate assembly as claimed in claim 6 wherein said bores are tapered to frictionally receive said wedged pin.
 8. A foot or top plate assembly as claimed in claim 7 wherein said pin is forcibly moved from the engaged position to the disengaged position while the foot or top plate assembly is under a compressive load urging the screw jack towards the base plate.
 9. A foot or top plate assembly as claimed in claim 8 wherein said taper is 3 degrees.
 10. A foot or top plate assembly comprising,a screw jack having a hollow end and a threaded end, said threaded end having an external thread adapted to receive a wing nut, said hollow end having a first bore of a first diameter and a second bore of a second diameter, said first bore in substantial alignment with the second bore, a base plate having a first and second support plate, said first support plate having a third bore of a third diameter and said second support plate having a fourth bore of a fourth diameter, said third bore in substantial alignment with the fourth bore, said first plate spaced from the second plate for slidingly receiving said hollow end of said screw jack, and a wedged pin for extending through said bores, said bores adapted to receive the wedged pin in a frictional fit, said base plate having a pin support member extending substantially perpendicular thereto and adapted for supporting said wedged pin intermediate of the first and second support plate, said wedged pin having an elongated cone shape having a taper for pivotally connecting the base plate to the screw jack, whereby as said wedged pin is moved between an engaged position and a disengaged position said base plate moves towards and away from the screw jack.
 11. A foot or top plate assembly as claimed in claim 10 wherein said taper is between 2 to 10 degrees.
 12. A foot or top plate assembly as claimed in claim 10 wherein said bores are tapered to frictionally receive said wedged pin.
 13. A foot or top plate assembly as claimed in claim 10 wherein said pin is forcibly moved from the engaged position to the disengaged position while the foot or top plate assembly is under a compressive load urging the screw jack towards the base plate.
 14. In a combination with a shoring structure or tower, a foot or top plate assembly comprising,a wedged pin having an elongated cone shape having a taper, a screw jack shaft having a hollow end adapted to receive the wedged pin in a friction fit in an engaged position, a base plate having a support means for receiving the wedged pin in a friction fit and adapted to receive said hollow end in a sliding fit, said wedged pin pivotally connecting the base plate to the screw jack, whereby as said wedged pin is moved between said engaged position and a disengaged position relative movement between said base plate and said screw jack is effected.
 15. The foot or top plate assembly as claimed in claim 14 wherein said taper is between 2 to 10 degrees.
 16. The foot or top plate assembly as claimed in claim 14 wherein said taper is 3 degrees. 